In the tillage of fields for farming it is known that a well tilled or plowed field is susceptible to wind erosion. It is recognized that if the field is not level there will also likely be water erosion. It further is known that both wind and water erosion can be minimized by not clearing and tilling the field too thoroughly. Part of the residue of previous seasons crop should be left to help to retain the soil in place.
However, it has been found that such mulch and rubble left in a field interferes with penetration of herbicide and other substances added to the earth by water spray. Some improvement can be produced in penetration by the use of higher pressures, but there is a practical limit in that above about 40 psi water sprayed from conventional nozzles tends to become a fine mist with practicallly no penetration capabilities, and which may readily blow away. Some improvement can be attained by adding excess water, but this requires almost constant refilling of water tanks on spreaders. Farmers are reluctant to stop to refill water tanks. As a result of all of the foreging, minimally tilled fields left with mulch and rubble tend to have herbicide and the like ineffectively dispersed therein.